15th January 1890
From: Lord Uriah Chetworth, Chetworth House, Cornwall
To: Archibald Jenkins, Bristol
Archibald,
Happy new year my young friend. I do hope you had a pleasant festive season, that your parents are well, and I trust that a brief sabbatical from your academic stresses has been to your benefit. After all, a new adventure awaits us, and we sorely missed your support on our last trip whilst you completed your studies.
As well you know from our previous correspondence, our intended destination are those darkest jungles of South America, and our objective botanical. However, those specimens so prized by our botanist cohort do not solely reside in the highest branches, but also are to be found in the rivers and swamps of this most sultry environment. To this end, to penetrate deep into the Amazon basin we must venture forth upon boats of a shallow draught, as required to traverse the local wetlands.
As you may be aware from newspaper reports of nearly a decade hence, I have previously travelled into such environments. During once such trip the shallow draught and the prodigious marine vegetation colluded to foul the screw of our steam motorised boat. Naturally, with a crew member to assist I ascended into the murk to free the propeller of weeds, but with a certain apprehension as the Amazon rivers and wetlands are teeming with wildlife that threatens both life and limb, from the fearsome carcharhinus leucas to the tiniest candiru that are actually known to swim up into those channels of a gentleman’s most sensitive parts. Both, I think you will agree, a fate no fellow would care encounter. On this occasion, we were immediately assailed by a black caiman of a size to which I was unaware they could grow. A crocodile was reported, but I assure you a caiman of uncommon size was indeed our assailant, as crocodiles are uncommon in that region. The crewmate who had accompanied me beneath the boat was seized, to be dragged away from our vessel toward an uncertain fate. Unwilling to harm man nor beast with rifle or pistol, and still below deck, from the water I requested a crew member toss to me a wooden oar with which I fenced the creature until it deigned to release our companion, who I quickly retrieved and assisted back into the boat. I quickly followed, and with a morsel such as I now beyond the reach of its powerful jaws, the creature soon tired of our sport and departed.
It occurs to me that we may similarly founder on our upcoming trip. As we must enter the water to free the propeller of detritus, might we conjure some means by which these threats may be held at arm’s length from our craft whilst we affect such repairs?
Thank you for your consideration upon this matter.
Your good friend.
Uriah
22nd August 1880
Bristol Gazette, Sunday 22nd August 1880
Chetworth fights enormous crocodile! The sinuous rivers of darkest Amazon jungles hide terrible beasts. Whilst on an expedition upriver, Chetworth and his crew had need to enter the unknown waters to free the vessel from weeds that had entangled their craft. Chetworth and his companion were submerged in their task, and the propeller was quickly freed of foul detritus. Then, just as they had completed their task and without warning, a gigantic crocodile lunged from the depths, grasped that crewmember who accompanied Chetworth and made off with this poor soul to make a breakfast upon his flesh! Thank the fates that this beast had not grasped Chetworth himself! With no thought for his own safety, Chetworth dove headlong after his rapidly retreating crew member, oar in hand. Catching the creature quickly, Chetworth clambered upon the scaled back of his opponent and around its head began to beat with the wooden oar. Picture the scene. Chetworth astride a beast with oar in hand wielded as the finest heroes of our nation might a chivalrous sword! Despite this furious onslaught, the ravenous lizard would not release its prize. Chetworth quickly surmised that greater motivation was demanded. Followers of Chetworth’s adventures will well know his interest in all things mechanical and had soon jammed the wooden oar between the mighty jaws of the beast to gain some leverage against his foe[1]. Grasping this mechanical advantage in both hands and with a brace made of his knees behind the head of the beast, Chetworth’s heaved mightily and inched the vice-like grip open the merest crack. The lizard knew that it had met its match, for it could not both grapple with Chetworth and retain its meal and soon released the crew member that it had so injured. The gravely injured man kicked feebly back towards the boat, and Chetworth knew he must distract the beast whilst his companion made his escape. Freed from its prize, and as crocodilian are known to do, the creature began its death roll! Chetworth, a champion wrestler, had little choice but little problem to cling upon the monster’s back as it turned. Dunked once, twice, thrice into the river’s murk as the reptilian steed rolled, Chetworth clung on! Legs wrapped about its middle, Chetworth pounded upon the creature’s back as it attempted to shake its rider loose. Chetworth maintained a weather eye upon his companion as he edged painfully back toward safety, and when the distance between the creature and its erstwhile meal seemed sufficient, Chetworth leapt from the monster’s hide and swam with a powerful front crawl, of which he is well known, towards his injured companion and towards safety. To prevent the beast from recovering its prize, upon reaching his patient Chetworth grasped the victim under both arms and continued his retreat in backstroke to better watch for a reprise in the crocodile’s attack[2]. The creature quickly gathered its wits from Chetworth’s assault, and before long our bold adventurer could see the black shape sliding lithely through the water towards the pair. Kicking the water with fury, Chetworth made it back to the relative safety of the boat before the crocodile struck home. However, this conflict was but complete for the injured party had yet to be hauled from the water. To facilitate the recovery of his crewmate Chetworth was obliged to remain below, to push from the waterline whilst others pulled from the deck. The beast had eventually gained upon the fleeing pair, and great jaws yawned open to crush Chetworth in its grasp. With no time to lose, a faster retreat was demanded. Submerged up to his chest in the water, Chetworth grasped the gunwale with one hand, and with his free arm made to hug his injured companion around the chest. With a commanding bellow from Chetworth the pilot of the craft was ordered to wide open the throttle of the steam motorised craft. With a roar. the boat now free from the weeds that had it so entangled did now leap away from the river monster and to drag Chetworth and his patient away from danger just as its jaws snapped shut mere inches from our heroic commander[3]. The monster gave chase! Clinging to the boat with a single hand, Chetworth delivered a final strong kick against the snarling snout of his pursuer, whilst the steam vessel sped the party to safety!
Plate 1: Considering the tone of contemporary news reporting of the time, it is hard to determine to what extent Chetworth’s exploits were exaggerated. Contemporary accounts from witnesses suggest this newspaper account entirely accurate.
[1] Block: Jaws crush and secure their prey. Block this harm with the oar.
[2] Separate: We must be in the water to fix the boat, but must not be in the water to avoid assault. Separate benefits from the harms by swimming away to find water that does not contain the harm.
[3] Improve: Swimming away from the harm solves the problem, but swimming speed is insufficient. Find a faster way to retreat from the harm.
1st February 1890
From: Archibald Jenkins, Bristol
To: Lord Uriah Chetworth, Chetworth House, Cornwall
Uriah,
I can well understand that you hold no enthusiasm to again battle such a reptile, and to this end, the question you pose makes a certain sense. You wish to enter the water to resolve problems provoked by the shallow draught and jungle weeds to be found beneath the surface. To this end you wish to hold the water creatures at bay, to separate them from that water local to your craft. However, to derive a good answer one must ask a good question. You present all manner of hazardous organism that inhabit a very wide variety of size scales, from gigantic predators to small and painfully inconvenient fish. I would even hazard that even smaller scales of hazard are complicit in the threat to our crew, as these waters will expose us to those bacteria and phage which may provoke hospitalisation. To place some agreeable distance between our craft and every hazard might demand that we simply withdraw from the waters and maroon our craft upon the banks of the river.
Rather than mitigate their effects, I fancy that a better question would seek to avoid an encounter with these harms altogether. You suggest that the craft be separated from river beasts. However, I note that once onboard you are safe from these creatures. The craft does not require separation from these hazards at all! We do not necessarily wish to place some agreeable distance between our craft these hazards. We wish to put distance between the crew and the waters. As a consequence, we must avoid entry into the waters, and the mechanism that provokes this action is the entanglement of the propulsive screw with the underwater flora.
In this, we find our contradiction. The propulsive mechanism must inhabit the river waters as do those plants that make their home thus submerged. If propeller encounters flora, a hazard ensues to draw the crew into the waters and into the jaws of whatever beast may lie in wait below. The propulsive screw must risk entanglement, and yet not become entangled. The propulsive screw must be immersed in the water, but also avoid immersion in these waters. How are we to resolve this conundrum?
Perhaps we might separate the screw from the fouling weeds by offering some barrier that can shield an encounter of one with the other[4]. A plough shaped device before the propeller might ease the weeds aside. However, this may ease aside the very water with which we wish to feed our screw. A porous shield that permits water whilst acting as a barrier to the jungle flora may offer an improvement[5]. Of course, to offer such a barrier will provide prior warning of the advance upon our propeller of the undersea jungle[6]. Perhaps we might connect this warning to the throttle of our motor. Hence, we could heed this warning, and deactivate our motor as the jungle approaches[7], to glide over the threat without entraining it into our propulsive mechanism.
Uriah, does your extensive marine experience and experience with the tropical climates bring to mind any alternative mitigations?
Archie.
Plate 2: Jenkins suggests a simple shield to prevent fouling.
[4] Separation Principle 11. Cushion in Advance. Prepare in advance a function that will mitigate potential harms, should they arise.
[5] Separation Principle 31. Porous Materials. Replace materials with porous substances. Fill porous materials with a beneficial substance.
[6] Separation Principle 9. Prior Counteraction. Counteract anticipated harms in advance.
[7] Separation Principle 23. Feedback. Feed information from the action back into the system. Change existing feedback. Increase automation.
20th February 1890
From: Lord Uriah Chetworth, Chetworth House, Cornwall
To: Archibald Jenkins, Bristol
Archibald,
Indeed, I seem to have asked the wrong question. As I read your correspondence and better directed a mesh that will permit water to pass but not permit troublesome weeds was also my first destination.[8] It is an obvious solution, but my sense for marine vessels is discomforted. Despite the porous nature of this hypothetical shield, does this projection into the water not introduce a definite disadvantage? A shield that can turn submerged weeds aside may surely turn aside some portion of the flow. Furthermore, a mesh sufficient to prevent access to weeds would surely become blocked by detritus, to further increase this deflection. This deflection of waters would feed the screw with decreasing material to chew upon as it clogs, and would also introduce drag forces that result in a vessel of inelegant design. Once more I am obligated to enter waters filled with hazards, of which I surely have little fear but for the inconvenience of mitigation. This shield does seem a compromise between propulsion and protection, of which you often warn[9].
I turn my attention to an alternative mean by which we could separate our propulsive screw from the infernal weeds. I strolled through the gardens as I mused upon this problem, and did visit the gardener of the grounds to discuss. After all, weeds are his business, and as you turn to my seagoing experience for support, I in turn head to the potting shed to seek expertise[10]. We talked for some time, and even considered for just a moment some ludicrous contraption of Budding’s design that might mow the weeds under the surface before they reach our propeller shaft. A ridiculous proposal, for sure, but for certain by that point we had imbibed a quantity of a potent snifter that my gardener brews in the potting shed from a variety of herbs and berries gathered from the grounds. This liquor is a tremendous stiffener, but incompatible with the solution to complex problem as our submerged lawn mower did have us in fits from which I had to eventually withdraw[11].
Once recovered some hours later, the scythe-like paddles of Budding’s device did mind me of the enormous paddle steamers I have observed laboriously swimming up and down the great Mississippi River in the United States. In this, the problem is solved[12], for these shallow draught boats prevent fouling by lifting from the water those parts of the mechanism that may become fouled with detritus, to dip the propulsive part into the water only as required[13]. Hence the propulsive shaft that may entwine the submerged weeds will never encounter these weeds to be so bound. Hence to separate propulsion from weeds, rather than project some obstruction into the water, we pull those parts so harmed by the flora from the water[14]. Of course, the passage through the Amazonian waters will be narrow and restricted. However, might a design of boat similar to, but shrunken from a river paddleboat serve our purposes?
Uriah.
[8] A separation by condition, to produce a filter.
[9] The mesh shield exhibits Benefit Induced Harms, to result in a compromise.
[10] Your ideas are not solutions. Your ideas are questions. Find an expert to answer these questions.
[11] Innovation is funny.
[12] Always seek prior art before attempting to solve a problem.
[13] Separation principle 2. Taking out. Extract and employ only the useful part, or separate the harmful part from the object.
[14] Separation principle 13. Do it in Reverse. Reverse a function. Implement the opposite action. Place an object the other way around or upside down or inside out. Start at the end, and work towards the start.
3rd March 1890
From: Archibald Jenkins, Bristol
To: Lord Uriah Chetworth, Chetworth House, Cornwall
Uriah,
It seems that you have solved the problem, for a paddle does remove those parts that may entwine from the local flora. Bravo, sir. As I illustrate, with paddles on wings projecting from either side of the hull, through differential rotation on either side we gain considerable manoeuvrability. This arrangement would allow the vessel to turn around its very centre. I do worry that the increase in width provoked by these outriggers may offer an impediment to entry into those narrow spaces of the Amazonian wetlands. I offer an illustration of a means to avoid this portly vessel, as this breadth may be mitigated with a stern-wheeler which mounts a paddle to the rear. As a consequence, the vessel retains a slim frame. Unfortunately, with the paddle placed astern we must return to a rudder to affect control, and so lose the manoeuvrability offered by the differential rotation of paddles placed to either side.
You have solved the problem, and are well served by a solution that already exists in the world[15]. However, I fear that you may have rejected one compromise, and replaced it with another. And besides, in your previous correspondence you made objection to an inelegance of the propulsive efforts, and the paddle boat is an inefficient means of propulsion when compared to the water screw. Furthermore, your great enthusiasm for speed we both know full well.
I propose a solution to our problem that draws upon the advantage you propose, to lift the working parts from the water, whilst employing a propulsive screw to drive the boat to high speed. I propose that we lift this screw entirely clear of the weeds that grow below, and lift this screw clear of the water’s surface entire[16]. To separate prop from weeds thus, we separate our propulsive device from the very working fluid that we employ to drive us forwards. With water absent, we must find some substitute in the environment to act as our propulsive medium[17]. The obvious alternative is the air itself, which we can drive behind us with a propeller mounted upon the hull of our boat as one might find employed by the airships of Wolfert and Daimler some two years past. As these aeronauts must also, a compact and powerful means to drive this propeller must be found. Although the steam engine may offer a familiar option for a marine vessel, I see no reason why we should not choose the very same option as our airborne brothers.
Rumour has it that the Priestman Brothers of Kingston upon Hull consider a petroleum motor as a viable means to propel a launch. This proposal may offer high power packaged into a small volume, which is an arrangement that I know will be of interest to you. I shall make enquiries with Priestman Brothers to determine if they do indeed have expertise in this regard of which we can make use. It seems very likely that this organisation will employ a propulsive screw as typical as one might find on any high-speed vessel. I shall present our alternative to determine if their marine motor might provide the desired thrust.
Archie.
Plate 3: Jenkins took great care to sketch the paddle wheel proposed by Chetworth, despite his intention to immediately reject the idea.
Plate 4: The use of petroleum motors to drive marine vessels was in its infancy in 1890. However, their employment in airships did offer Jenkins a model with which to propose an air driven vessel.
[15] Never reinvent the wheel, unless the wheel does not serve your needs.
[16] We remove the propellor from the harm entirely with separation principle. 2. Taking out. Extract and employ only the useful part, or separate the harmful part from the object.
[17] Check your resources. If a function is absent in the problem space, list all other resources in the problem to determine if any may substitute for the loss.
15th March 1890
From: Lord Uriah Chetworth, Chetworth House, Cornwall
To: Archibald Jenkins, Bristol
Archibald,
Good gracious, I don’t know whether to be impressed or appalled at your proposal. Your whirligig may indeed drive our vessel to some prodigious speeds and is an experience I would very much like to enjoy. However, I fear that you have failed to correctly picture the environment through which our vessel must penetrate[18]. The wide and open trunk of the primary Amazon waterway may present to us the opportunity to open the throttle wide and skate over those waters disturbed by neither tide nor waves. However, off the main thoroughfare, the extensive swamps of the Amazonian jungle will demand a more cautious advance. Whilst you successfully mitigate the threat from submerged flora, you fail to picture the vegetation above[19]. Those aeronauts can afford to propel with blades that thrash at the air, for in the heavens there is little in the locale against which they may hack. Upon our journey into the swamp regions, above and beside our vessel will hang all manner of creeper, vine, and branch that will either once more entwine our propeller as the submerged weeds might, or simply smash asunder.
Forgive me for shooting down your proposal so directly as I might a pheasant. I shall, of course, direct the gentlemen of the house manufactory on the grounds to consider how such a device might be constructed. Furthermore, the currency with which I pay for this criticism is found in an alternative based upon your solution. If we indeed lift our propulsive screw from the water entirely, might this translated propeller be accompanied by some portion of the waters that it must propel? The gardener’s current brew continues to draw me from the main house to spend some time with the staff on the grounds, and the lawn cutting device continues to draw my eye. In particular, if these helical blades become shrouded by a pipe of close fit, might we draw river waters up into the hull of the boat and through this pipe.? These blades could then be motivated to drive these captured waters down the length of the boat within some suitable pipework, to be expelled at the rear. I offer a sketch to illustrate my intentions, to present a boat that can draw the river into its body and propel waters as a squid might to make its escape[20].
If such a device can be constructed, with waters motivated by those developments in Kingston upon Hull that you hope to secure, additional function can be found in the nozzle that expels these driven waters. We recover the manoeuvrability offered by the winged paddle boat by directing this nozzle to and fro to the left and right of our stern. This jet can then turn our bout about its centre as you describe.
What say you? Could we propel our boat as might a squid?
Uriah
Plate 5: In 1890, all of the necessary prior art was available in the patent record for Chetworth to propose the water jet powered boat.
[18] If you are only imagining the customer’s problem, then you build a structure upon sand. Get out of the building, interview the customer directly and assemble an accurate model of the problem based upon real evidence.
[19] Think widely in time and scale to avoid a singular focus upon the central problem. If you don’t consider the wider context you solve one problem only to stumble headlong into another.
[20] Look to nature for inspiration.
30th March 1890
From: Archibald Jenkins, Bristol
To: Lord Uriah Chetworth, Chetworth House, Cornwall
Uriah,
My apologies for my previous effort. I have yet to travel into those dark jungles and so inexperience with the terrain seems to have led me astray. Do keep me informed on the conclusions of the manufactory. It is so often the case that a solution drawn only in conceptual terms may seem conclusive, only to fail when practical considerations of their construction are attempted[21]. If you could inform the gentlemen of the house works that Priestman’s are indeed working upon a launch propelled by a petroleum motor. However, although not spoken aloud I suspect a sceptical eye was passed over our proposal to propel a waterborne vessel with air pressure alone, as might an airship.
Your squid-like boat is intriguing. You employ a screw to propel the craft, and not only separate this shaft from those weeds affixed to the rover bottom but also resolve the need to enter the waters should this rotary mechanism become fouled by floating detritus. I would continue to recommend a mesh filter be placed within the flow. However, as per your design, this filter may too be raised inside your plumbing to be accessible from within the hull of the vessel. Two problems, however, remain. The helical blades you borrow from Budding may suffice to drive water, as might the screw of Archimedes. However, this impeller is unlikely to drive much pressure into the air itself. To charge your pipework water must first be raised into the mechanism whilst air is expelled from every chamber. This may be achieved by some preliminary pressure driven by a piston to set the whole device free from air before propulsion might be achieved. The second problem is one of your own suggestion. This impeller will remain assaulted by the detritus to be found in most rivers which will demand a filter upon the inlet that not only must be frequently cleared but also will turn aside the very water with which we wish to feed our engine. Or design would be improved if our impeller not only provoked water to move but was also entirely permeable to any solid materials that pass through the pipework. A contradiction indeed!
Despite my recent adventures in the investigation of the petroleum propulsion of motor launches, consideration of piston and pump to charge our device minded me once more of the more traditional steam engine more commonly used to propel a boat. Mistress steam has served us well this century, and so I see no need to reject her service just yet. In my efforts to design an impeller both impermeable to water but also permeable to solid material, it occurred that water itself possesses this property. An impeller constructed from water itself would serve us well[22]. With the pipework of your design charged with river water, if we were to replace your helical impeller with an injection of steam, might this fast-flowing jet encourage the Amazon to pump through your raised plumbing? If so, detritus sucked from the depths might pass right through the guts of our motor unimpeded.
An experiment to this end is definitely in order! If the time is convenient, I shall catch the next train to Chetworth House upon receipt of your reply.
Archie.
Plate 6: Jenkins modifies Chetworth’s turbine to offer the same, but with no rotating parts. A steam injector entrains river water, forcing it through the pipework.
Plate 7: Jenkin’s design is reversible, to offer a braking mechanism and to purge the pipework of blockages.
Plate 8: Steam power is delivered by a simple boiler of established design.
[21] Your ideas are not solutions. Your ideas are questions for the laboratory.
[22] Separation Principle 33. Homogeneity or Uniformity. Manufacture subcomponents from the same material or from materials with the same properties.
13th April 1890
From: Lord Uriah Chetworth, Chetworth House, Cornwall
To: Archibald Jenkins, Bristol
Archibald,
Remarkable. I have directed to gentlemen of the manufactory to stop work immediately on the airboat, and apply their considerable skills to the construction of your steam injector proposal, in miniature[23]. My word, how the gentlemen did grumble at this change of plan[24]. The workshop were very much looking forward to testing your air powered boat on Chetworth lake. However, the novelty of your idea supported by a short and inspiring speech from yours truly soon turned them to our cause.
The pipework you propose does seem somewhat slim for the proposed detritus filled waters. However, perhaps that steam jet will indeed pulverise those more frangible particles as they pass through the guts of your system. On a related theme, I note that you offer two mechanisms to slow the vessel, for the reverse thrust is duplicated by the simple act of turning the tiller to the rear, to direct our rotating nozzle to the bow. To be sure, I would not fancy turning the tiller so sharply whilst moving at speed under a full head of steam, and the reverse flow does offer a convenient means to purge the innards of jungle debris. Hence, this duplication seems justified, but perhaps our preliminary experimentation can eschew this redundancy whilst we determine if the propulsive mechanism might function as desired?
I am particularly pleased that we return to steam as a mechanism to deliver power to our endeavour. The raising of steam is a technology of which I am very familiar, should our device develop a fault far from civilisation. Furthermore, the steam boiler will burn any fuel. I was at first attracted by the power and speed potentially offered by a launch powered by petroleum. However, to venture many hundreds of miles into the jungle thus powered would demand that we carry with us a sufficient supply of petroleum to return us from our venture. To supply a furnace to boil waters drawn from the very medium upon which we float, we merely reach into the forest that surrounds us for fuel[25]. As a consequence, the only consumable that we cannot draw from the environment through which we traverse are those mechanical spares required should components become damaged or worn from use. I note also that the boiling of river waters to propel our vessel will also provide us with a plentiful supply of purified waters to drink. If we consider the perils of such arboraceous waters that teem with life, the purification of our supplies will avoid the need for purgative or our own, as possessed by our propulsion[26]. I am keen to determine if this device might function as desired[27], and would be very much obliged if you could catch the next train to Chetworth House, at your convenience. You should find rail passage for your journey behind the ticket window upon your arrival at the station.
Many thanks for your efforts.
Uriah.
[23] A small experiment need not consume all of your funds. Learn what you must, and no more.
[24] If you have evidence to support a change of direction, then pivot. There are no prizes for throwing good money after bad.
[25] Don’t be seduced by new technology. Established prior art is established for a reason.
[26] The hook offered by unexpected, auxiliary functions can serve to sell a new idea well.
[27] Ideas are only questions. Solutions are offered through experimentation.
Jetboat: Historical context
Neither Jenkins nor Chetworth invented the airboat nor the steam powered jetboat. Both means of propulsion arrive in the historical record somewhat later than 1890. However, sufficient prior art is available in the patent record to assemble these devices should a search of this database have been as easy in the 19th Century as it is today.
The use of filters to project the propulsive screw is obvious, and the paddle powered ship is to Chetworth and Jenkins an established and well-understood technology. The invention of the airboat must wait fifteen more years, and the motivation for its development is perhaps more interesting than the fiction penned above. In the infancy of aeronautics, means were developed to test the thrust of motors required to propel early aircraft into the skies. One such method involved the construction of waterborne pontoons upon which suitable motors were mounted to act as floating laboratory.
The first airboat was invented in 1905 in Nova Scotia, Canada by Alexander Graham Bell (1847 - 1922), a Scottish-born inventor, scientist, and engineer who is credited with inventing and patenting the first practical telephone. Bell developed a catamaran vessel, the Ugly Duckling shown in Figure 1 propelled by an aircraft propeller driven by a water-cooled aircraft engine weighing 2,500 pounds (1,100 kg). This motor was able to drive a boat to a maximum speed of 4 miles per hour (3.5 knots), although Dr Bell correctly predicted that such as vessel could have a much higher top speed. Modern commercial airboats will typically cruise at 35 miles per hour (30 knots), but modified airboats can go as fast as 135 miles per hour (117 knots)
Figure 1: Dr Alexander Graham Bell on board the airboat, Ugly Duckling.
To identify the invention of the jet boat, in which propulsive waters are drawn into the hull of a vessel by an impeller and then expelled from the rear, is an altogether more curious story. Typically, the invention of the jetboat is attributed to Sir William Hamilton in 1954. Hamilton was provoked to this design of boat propulsion by a desire to navigate the fast flowing but shallow rivers of New Zealand. However, a review of the patent record reveals a considerable number of examples of such propulsion that could serve to inspire Chetworth and Jenkins nearly 70 years earlier.
· US1899 An Apparatus For Propelling Boats, &C., By Means Of Jets Of Water, Draw In And Forced Out By Pumps, granted in 1840 to Hugh I. Ronalds, of Illinois. Ronalds notes that even in the early 19th Century, numerous attempts had been made to propel vessels by the reaction of water forced out through cylinders in the direction of their sterns.
· US79937, An Improvement In Propelling Vessels, granted in 1868 to B. T Babbit, in which a jet of compressed air acts upon water in a submerged tube, drawing from the bow and propelling this water astern.
· US117504, an Improvement In Hydraulic Motors granted in 1871 to Arthur Barbarin and Joseph ALBRECHT, M.D., of Louisiana.
· US117505, a further Improvement In Hydraulic Motors granted in 1871 to Arthur Barbarin and Joseph ALBRECHT, M.D., of Louisiana.
· US119363, an Improvement In Propulsion Of Vessels granted in 1871 to Henry Jackson, of New York. The steering mechanism offered by this device is copied by Jenkin’s fictional invention.
· US132262, An Improvement In Reversible Hydraulic Propellers granted in 1872 to Ransom G. Dunbar, of Indiana.
· US134730, a Means for Propelling Vessels granted in 1873 to Henry C. Camp, of Minnesota,
· US138665, an Improvement In Propulsion By Gas Explosions granted in 1873 to William Augustus Leggo of Quebec. A design that exhibits similar properties to the pulse denotation jet engine that drove early jet aircraft in the mid 20th Century.
· US146266, an Improvement In Marine Propulsion granted in 1873 to John S. Morton, of Pennsylvania
· US167641, Propelling Canal-Boats granted in 1875 to Almond Bugbee, of Indiana.
· US213101, a Hydro-motor granted in 1879 to Dr Emil Fleischer of Germany.
· US247679, a design for a Hydraulic Propeller granted in 1881 to Hugh Mulhollen of Pennsylvania.
· US243184, a design for a Hydraulic Propeller granted in 1881 to George Edgar Whipple of New York. Whipple appreciates the harms caused detritus entering the system, and employs multiple small inlets arranged near the surface of the water to avoid ingestion of grit.
· GB10036, Improvements In The Means Or Apparatus For The Propulsion Of Boats Or Vessels By Jets Of Water, granted in 1895 to Jules Hippo Corthesey of Surrey, UK.
· US516419, a Means For The Propulsion Of Vessels granted in 1894 To William. H. Witte, of New York.
· US565359, a Mechanism For And Mode Of Marine Propulsion granted in 1896 to Sidney Lawrence, of Victoria
· US617969, a Hydraulic Propeller For Ships granted in 1899 to Andrew Plecher, of Virginia, comprising a helical impeller much like Chetworth’s helical invention. This impeller is also employed as a bilge pump.
· US646391, a Hydraulic Propelling Apparatus granted, in 1900 to Frank W. Simmons of California.
· US671089, a Hydraulic Propeller granted in 1901 to John Sketchley Morton, of California. Morton also notes that in the event of a breach on the hull, a hydraulic pump for propulsion can be transformed into a powerful bilge pump.
Of note is US431090, a means of Hydraulic Propulsion granted to Frank. G. Waterhouse of Pennsylvania in 1890. The Waterhouse design offered inspiration for Chetworth’s helical screw. Of note, Waterhouse offers a number of intriguing novelties beyond Chetworth’s simplified fictional efforts and is illustrated in Figure 2. Waterhouse proposed that a paddle, B, turns inside the casing but has no pitch. The paddle will simply revolve the water within the tube without propelling it to the rear. Helical blades fixed to the internal surface of the tube deflect this revolving water to the rear to provide thrust. This arrangement therefore delivers thrust not from the revolving screw but from the fixed cylinder that surrounds it. The purpose of this arrangement is to ensure that no fore or aft loads are presented to the bearings of the rotating impeller. A beautiful example of Separation Principle 13[28] to separate the propulsive loads from the rotating parts.
Figure 2: Waterhouse unloads the bearings in an ingenious manner.
Jenkin’s illustration of boat propulsion driven by steam injector is drawn in its entirety from US286477, Hydraulic Motor For Vessels, granted in 1883 to Simon O’Brien, from Rhode Island. This patent will provide a new and improved motor for marine vessels, in which the steam is applied in the most direct way and with very little machinery. The invention consists in a motor formed of a series of pipes and a cock so connected that water can be drawn in at the bottom of the vessel and forced out at the rear end of the same, whereby the vessel will be moved forward, or water can be drawn in at the rear end of the vessel and forced out at the bottom of the same toward the front end, whereby the vessel will be moved backward. The invention also consists in attaching a hose or flexible pipe to the end of the pipe projecting from the stern, and also attaching the said hose to the rudder, whereby the water issuing from the said hose will assist in steering the vessel. O’Brien’s design is illustrated in Figure 3 and is realised in Jenkins fictional illustrations.
Figure 3: US286477. By means of my improved motor the complicated machinery used heretofore can be dispensed with. There is but very little wear and tear.
[28] Separation Principle 13. Do it in Reverse. Reverse a function. Implement the opposite action. Place an object the other way around or upside down or inside out. Start at the end, and work towards the start.